Electronic systems and circuits have made a significant contribution towards the advancement of modern society and are utilized in a number of applications to achieve advantageous results. Controlling voltage and current in the electronic systems and circuits is typically very important and failure to adequately control voltage and current can be detrimental. In particular, overload or short circuit conditions can have adverse impacts. Adverse impacts associated with an over load or short circuit condition can include over heating or temperature issues. However, traditional attempts at controlling current can be ineffective at preventing damage and often introduce other undesirable impacts or side effects.
Some traditional approaches to current control attempt to implement current limiting. FIG. 1 is a diagram of an exemplary traditional system. Current limiting is a feature that is more and more attempted in various switch applications. Protection measures should be engaged as quickly as possible for good protection of both the source (e.g., power supply, etc.) and the load. When a circuit detects an overload or short circuit condition, traditional protection approaches typically attempt to shut off the device or system experiencing the overload or short circuit condition. Conventional approaches to shutting off a device may provide overload protection. However, shutting off a device or system typically has undesirable side effects of interrupting utilization of the device or system.
Traditional approaches to current limiting typically give rise to a number of issues. Due to the advantages of a very low on resistance between drain and source of a transistor when operating as a switch that is in an on state (Rds-on), it is often desirable for a device to be designed with high transconductance. However, a high transconductance (gm) can translate into a low gate to source voltage when the device operates in a current limit mode. In this region of operation (e.g., low VGS, and high VDS, etc.) power devices typically exhibit improved or maximum sensitivity to threshold voltage reduction caused by temperature increase. A positive detrimental feedback effect often occurs since local temperature increases cause reduced threshold voltages which then leads to additional increased current that causes a further increase in temperature. This positive feedback usually leads to thermal runaway in which a localized region of a MOSFET is damaged. As a result, when going into traditional current limit mode, power devices can be susceptible to being easily damaged. Some conventional approaches attempt to utilize components that have restricted or unfavorable characteristics (e.g., ineffective or reduced performance characteristics, poor gain characteristics, etc.).